System of coding and decoding



Nov. 29, 1938. w, s. LEMMON ET AL SYSTEM CODING ANDDECODING Filed May 22, 1956 16 Sheets-Sheet l i Nov. 29, 1938. w. s. LEMMON ET AL SYSTEM OF CODING AND DECODING Fi led May 22, 1936 16 Sheets-Sheet 2 ATTORNEY Nov. 29-, 1938. 'w. s. LEMMON ET AL v SYSTEM OF CODING AND DECODING Filed May 22, was 15 "Sheets-Sheet} FIG. 3,

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SYSTEM OF CODING AND DECODING Filed May 22, 1936 16 Sheets-Sheet 12 WWW N; BY Q A Ll ATTORNEY Nov. 29, 1938. w s. LEMMON ET AL SYSTEM OF CODING AND DECODING Filed May 32,1936 lGSheets-Sheet 1s mmw M 3m 1 E T Rs BY My. W

' ATTORNEY Nov. 29, 1938. w. s. LEMMON ET AL 2,138,639

I SYSTEM OF CODING AND DECODING Filed May 22, 1936 16 Sheets-Sheet '14 ATTORNEY Nov. 29, 1938. w s, LE N AL 2,138,639

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Filed Mag, 22, 1936 16 Sheets-Sheet 16' IVEN;OR$ I 11 BY YWFQQ ATTORNEY JUL 25 NlTE STATES PATENT OFFICE SYSTEM OF CODING AND DECODING Walter S. Lemmon, New York, Charles R. Doty,

Binghamton, Richard F. Walz, Endicott, N. Y.,

- York and Albert C. Holt, Princeton, N. J., assignors to International Business Machines Corporation, New York, N. Y., a corporation of New Application May 22, 1936, Serial No. 81,178

'75 Claims.

This invention"relates to the art of secret writing and more particularly to a new system for transforming language messages into decodable secret code.

'An object of the present invention is to provide an improved system for the more rapid and accurate coding and decoding of characters or signs used in various communications.

Another object of the invention is to prevent periodical recurrences by causing irregularities in the coding process by a new system so as to introduce a new order of complexity of code according to an arbitrary system.

A further object of the invention is to produce a resultant which is most complex but' whereby the coding and decoding operations are simplified.

Still another object of the invention is to provide an apparatus which will automatically code a message as a result of the mere typing of the uncoded message, and which will automatically decode the message as a result of the mere typing of the coded message.

Heretofore, in order to prevent periodical recurrences in forming unintelligible sequences of characters in a coded message and to insure a continuous variation and transposition of the recoding drums or wheels which are adapted to be actuated? differentially to alter the circuit connections or the system. It has been found that systems of this type are apt to become quite complicated and tend to reduce the over-all rate of speed of operation and efiiciency of the systems.

In contradistinction to the present systems, the invention to be disclosed is based on the principle of a copending application, Serial No. 39,294, filed September 5, 1935, in which a single coding commutator or circuit changing device for a series of characters or signs is employed and to which, at variable times, a definite movement is imparted to alter, at irregular intervals, the circuit connections of the system. The complete series of characters or signs to be employed in a system may be connected to a single circuit changing device or may be divided into separate groups of characters and signs, and employ a circuit changing device for each designated group and treat each group device as a single coding commutator to further complicatethe resultant coded message. For the purpose of obtaining operation at irregular intervals of a coding commutator or wheel, control means are provided to shift the coding or typing circuits in an odd manner and in accordance with a varying and arbitrary pattern.

In addition thereto, provision ismade whereby the character sequence of the coding commutator is altered automatically to further increase the resistance of the coded message.

Other features and objects of the present invention are: to type the message in clear text and in a coded form simultaneously; to insert portions of a message in clear text at both the typing and coding positions; independent control means for the coding commutators to separately and irregularly position each commutator; the method of controlling the various control elements depending upon the frequency of operationof the operating or primary unit; the commutator control means being provided with removable control elements, and including means whereby certain control units thereof. may-be variably and arbitrarily positioned; means to lock the carriage return mechanism during the typing cycles; means to lock the character keyboard and release the carriage return mechanism at the end of a predetermined copy; error detecting circuits to prevent release of carriage return mechanism if control units failed to respond correctly during the typing of the predetermined copy; means to lock the keyboard and carriage return upon completion of a group of lines of predetermined copy; test key operation to return carriages automatically to left margin position if control units functioned correctly; recording at both units a symbol indicative of correct functioning on both clear and coded copies of text; error key operation if error was made in functioning of the control elements during the typing of said group of copy; re-alignment of coding control units to last text position, if error made; recording a symbol indicative of error function on both copies; at end of group and if coding units functioned properly, additional coding control units to be actuated, if an error had been made the said coding control units are not actuated; insertion of automatic spacing in coded text; substitution of additional character for space character in coding operation and provision to render the said additional characters inelTectiVe-in decoding; certain coding control elements operated upon recording of every character; multi-position key to control types of coding and decoding and insertion of clear text on both copies at any time; single control key means for changing from coding to dealign all the coding control elements to a normal reference point; dialing means to alter the normal reference point.

Further and other objects and advantages will be hereinafter set forth in the -accompanying specification and claims, and shown in the drawings, which by way of illustration show what is now considered to be the preferred embodiment of the invention.

In the drawings:

Fig. i is a plan view of the powe coding control elements.

P Fig. 2 is a detailed view of the coding commutators control device.

operated Fig. 14 is a fragmentary, sectional elevationillustrating a portion of a power operated typewriter inoluding certain control features.

Fig. 15 is a detail view of the carriage contact bar and brush arrangement.

Fig. 16 is a detail view of the keyboard locking arrangement.

Figs. i l, 17A and 173 show the circuit arrangement for controlling the coding control elements.

Fig. 18 shows the correct figure layout for Figs. 17, 17A and 17B.

Fig. 19 shows the correct figure layout for Figs. 20, 20A to 20D.

Figs. 20, 20A to 2ilD show a preferred arrangement of the typing circuits for coding and decoding operations.

Fig. 21 is a layout of the plug arrangement for the coding commutator control device.

The illustrative embodiment of the invention includes two typewriters to be interconnected for coding purposes. The apparatus is efiective, when the uncoded message is typed, to produce both a correct writing of the "copy and a writing of the same message in code, and, when the coded message is typed, to produce a correct writing of the code message for comparison with the copy and a correctly typed translation of the code message. To present the invention as briefly and concisely as possible, the independent control units of the system will be described first and followed by a description of the circuit arrangements and operation of the system.

Recording units 4 The system as illustrated herein comprises a primary typewriter,'upon which the messages to be translated are typed and recorded and may be ings 4- arranged in guideways provided therefor in the carriage and frame of the machine (refer to Fig. 1%).

greases Type bars 5 are pivoted in a type basket 8 in the frame of the machine and are provided with types "3 adjacent their free ends adapted to engage the platen or thework sheet thereon when the type bars are swung on their pivots. Power driven devices are provided for operating the type bars or other printing instrumentalities oi the machine. Said devices comprise actuators in the form of hell. crank levers 3 pivoted on a common pivot rod 9 and having one arm connected with an arm of a bell crank lever it by means of the link i2. The bell crank lever ii is pivoted 'on the common pivot rod i3 and its other arm it is connected with the free end of j a toggle lever i5 by means of a link it. The lever Fig. 3 is a detail of one of the control elements of the commutator control device.

it is pivoted to the am it of the type bar, and at its other end is pivotally connected with the free end of a toggle link il, pivoted on a fixed part of the frame. A spring it connects the arm it oi the bell crank with a fixed part oi the frame and resiliently maintains the parts in the normal position as shown in the figure oi the drawings, in which the type bar is retracted and the toggle it, ii is in straightened position. When the sctuator lever t is swung to pull the link it, it opcrates to swing the lever it in a direction to break the toggle and swing the type bar into printing engagement with the platen. I

The bell crank t has an arm it projecting downwardly on the free end of which a cam ii is revolubly mounted adjacent to the surface of a power driven roller 22. A spring-pressed arm 23 engages a. lug Ed on the cam and tends to swing it on its pivot into engagement. with the roller or a projection 2t thereon into engagement with a stop 25 on a detent'lever 26 pivoted on the hell crank t. At its upper end, the-lever 26- has a lateral projection whereby it is engaged by the slotted end of an am 2'6 projecting downwardly from a key lever 28.

The key lever is pivoted on the common pivot rod it and has a key '29 whereby it may be manually operated. A spring 3d connects the key lever with a fixed part and resiliently maintains the key lever and parts connected therewith in the normal position as shown. When the key is depressed, it swings the detent lever to move its stop 25 out of the path'of the projection 2t and permits the cam to turn under the action of the arm 23 into engagement with the roller. The cam is then rotated by the roller and swings the lever- 3 to swing the bell crank H, which swings the type bar into engagement with the platen. when the type bar is actuated to print, it engages the universal bar 38 to release the escapement mechanism, shown generally at 82, of the carriage 2. ,The parts thus far described are, or may be, of usual construction and form no part of the present invention except as they enter into combination therewith.

Attached to the rear section of the carriage 2 is a transverse bar 83 preferably of insulating material, the said bar is adapted to extend the entire length of the carriage. Superimposed thereupon-is a conducting bar or segment 3% having a plurality of slots 35 formed therein to expose sections of the insulating member 33 as shown in Fig. 15 of the drawings. A pair of brushes it supported in a fixed bracket 37, which is attached to and supported by the frame of the typewriter,

are adapted to cooperate with the contact bar it.

The slotted or insulated sections of the contact bar are so arranged that when the typewriter carriage is positioned to start typing on the work copy, that is, when the'carriage is at the left characters, or signs, for example 45 characters, the slotted section 35a. will be positioned so th at one of the brushes'36 engages the insulated section 33 and likewise after typing an additional number of characters, again, forexample, 8 characters, or signs, the slottedsection 351) will be positioned so that one of the brushes 36 engages the insulated section 33. Therefore, it will be understood that the carriage position at the left margin position or after typing 45 or 53 characters or signs is eifective to open the circuits connected to the said brushes. It is to be noted that the carriage position contact arrangement is provided on both the primary or operating unit and the secondary or translating unit, the purpose of which will be understood as the description progresses.

Atttached to the free end of arm it of bell crank lever B is a bracket 38 supporting a follower'roller 39 which is adapted to actuate the spring blade of suitably positioned contacts 40 or ii to close said contacts when the said cam 2!, controlled by a corresponding key 29, is released and actuated by the power driven roller 22. The single and double types of contact arrangements are shown cooperating with the said roller 39 for the reason that certain keys upon their depression control several dlfierent circuit arrangements which will be explained later herein.

Provision is made to operate the key bars 28- automatically by the solenoids 42 supported by the frame of the unit which are connected to the key bars by links it. It is also desirable to provide'means for looking all the keys against depression except the key bar depressed. To this end, a slotted trough or member 36 is arranged beneath the key board section of the unit. Arranged in,the trough is a plurality-of rollers db.

The combined diameter of the rollers 65 is such that they contact each other and the ends of the trough when a key bar is depressed and inserted between two adjacent rollers. It will be noted that by this arrangement it is impossible to depress two keys at one time, or to depress another key bar while a key bar is depressed. At certain intervals during the operation of the system it is desired to lock the keyboard so that certain character and sign key bars cannot be depressed, yet permitting certain other key bars to be free to be depressed. And at other intervals it is desirable to ,lock the entire keyboard preventing the depression of any of the character or sign keys.

I To accomplish this, the keyboardmay be divided into several sections with corresponding key bar locking means. For example, the carriage return key 29a and its key bar 28a are provided to be controlled separately; .to this end, a separate trough section Ma is provided, and cooperating with the rollers of this section is shown a dummy key bar 28b which upon depression by a corresponding solenoid and link arrangement 63 prevents the carriage return key from being depressed. It is possible to utilize existing key bars as dummy key bars without providing additional ones therefor, such as the key bars for the back spacer or tabular keys. Similarly, dummy key bar rte con trolled by a solenoid and connecting link lid, is adapted, upon its depression to lock the entire remaining section of the keyboard, preventingth depression of any of the keys 29.

, the controlling electron i General layoutdescription of controlling units Referring now to Fig. 1 of the drawings, a brief description of the layout of the power driven controlling units will be given. Supported on a suitable main base $6 is a driving motor it which is connected to a main drive shaft 68 through a suitable gearing arrangement and shown as a gear box 49. The said main shaft is suitably supported by the bearing frames 59. Clutch units which will be described hereinafter are provided and positioned along the shaft 48 and adapted to transmit power to separate units through its associated worm sleeve 52 .when the clutch unit is actuated. A coding commutator control means, generally designated 53, is mounted on the main base 46 and adapted to be driven by the main shaft through'an intermediate shaft 54. A coding commutator 55 for one group of characters or signs in the series is provided and adapted to a be driven by the main shaft through the associated intermediate shaft 56. A second coding commutator 57 for another group of characters or signs in the series is provided and adapted to be driven by the main shaft through the intermediate shaft 58 associated therewith. It is to be understood that one coding commutator could be provided for the entire series of characters and for signs to be included in the system. Whenever the case is such that two or more separate coding commutators are provided for separate groups of the characters or signs of the series. it is not to be confused with the multiple coding commutator arrangement usually in cascade, which are arranged so that one commutator, which must provide for the entire series of characters.

is positioned with respect to another adjacent typing circuits separately and not in a series re-' lationship. The individual controlling units will now be briefly described.

Clutch. units Referring now to Figs. 1, 2, 11, 12 and 13 the clutch unit 5! associated with-the coding commutator control device 53 will be described, however it is to be understood that the description thereof also applies to the clutch units bio and Blbassociated with the coding commutators.

The clutch units are provided to impart a step by step movement to the associated mechanisms at certain intervals and at other intervals to impart a continuous movement or rotation to the said mechanisms, depending solely upon the controlling impulse, and are similar in construction to the clutch described in a copending Patent 2,116,683 granted May 10, 1938. In addition thereto, it has been found that to insure a more positive operation of the system, the step by step movement is not imparted to the said connected mechanism until the decay of the control impulse, that is upon the deenergization of the controlling electromagnetic means. In contra- :distinction thereto the continuous operation of the clutch is efiected directly upon the initiation or the impulse, that is. upon the energization of etic means.

, 09 and did arranged asshown inthe figures so that the stop M is positioned below the stop 409 but not in thesame plane.

The purpose of the described arrangement is to efiect the intermittent and continuous clutch operation referred to. Energization of the coil 400 which hereinafter will be referred to as the clutch operating coil causes its armature 403 to 'be attracted. The movement imparted'to the armature 403 is sufficient to withdraw the stop 609 to permit the restrained stop pawl to advance or drop to the stop Mil as the armature is attracted, but the movement is not great enough to permit the stop pawl all to pass the lower stop Mil with the armature in the attracted position. Upon deenergization of the said coil 400 or upon the decay of the impulse, the armature is returned to normal position as shown permitting the stop pawl dil to drop off the stop Md and be advanced so that the coupling pawl 2 may be engaged with the ratchet wheel M3 to operate the clutch unit. This action is similar to the usual escapements for similar devices. Ratchet M3 is mounted on the continuously rotated shaft d8. Rotatably mounted on the said shaft'is a worm sleeve section 52 which may be secured or be an integral part of disc QM which is suitably attached to the clutch drum M5.

The said drum rotatably mounted on shaft 68 is provided with an arcuate opening (H6 and also is adapted to revolubly support on the shoullder M! a plate M8. The said plate is provided with a plurality of stop pawls 3, in the figures as shown four are provided. The plate M8 is provided with two openings, one Opening at M9 so that a. pin Q20 pivotally attached to one end of coupling pawl M2 may be inserted therethrough to extend into the arcuate opening of the drum M5 wherein the spring 52! which is attached at one end to the drum section and at the other end to the said inserted pin 120. The other opening M2 in the plate is an elongated one as shown through which a pin 32% is inserted and secured to the drum 5 i 5. The free end of pin MS has one extremity of the coupling pawl pivotally mounted thereon. The drum M5 is also provided with a plurality of recesses or notches 62d adapted to be engaged by a spring pressed pawl M5 mounted on plate $02, the purpose of which is to lock the clutch in its inoperative position when engaged by the said pawl. A pluralityof cam rollers #525 are mounted on the disc did and are engaged by an arm 627 pivotally mounted on plate 402 and urged to engage the cam rollers through theagency of spring @528. It is seen from the position of the various clutch elements in Fig, 11, that when the stop pawl is released by stop 409, the

spring 428 through the vpin 328 urges the plate sit to be advanced, this movement is restrained 1 by stop did before the plate M8 is advanced far tion and the stop pawl is again released by stop M0, the spring 32i urges the plate M8 forward to such an extent as permitted by elongated opening 422 which is sufficient to permit the coupling action, causing the sleeve section 52, drum M5, plate M8, pawl M2 and ratchet did to rotate in unison.

It is seen that the clutch unit is prevented from being rotated more than one quarter of a revolution. This is due to the stop pawl 8H arrangement. Upon completion of the quarter revolution rotation of the unit one of the stop pawls fill engages the stop 809 which in the normal position is in the path of the stop pawls to disengage the coupling pawl M2. At the moment of contact of stop pawl and the stop the coupling pawl is still engaged to drive the drum M5. The slight additional rotation of the drum causes the pawl M2 to be lifted out of engagement with the ratchet teeth because when the plate flit is blocked or restrained by stop M9, the pin 420 then becomes a fixed axis or pivot for the coupling pawl the other end of which is advanced in a forward direction due to drum 315 and the pin $28. An additional movement is imparted to the drum section M5 after declutching has been effected by the action of the spring pressed arm M1 on one of the cam rollers 426. The purpose of this additional movement is to advance the drum M5 ahead so that the pawl 425 engages the notches 62d in the said drum to lock it in the declutched or inoperative position.

The description thus far related to the intermittent or step by step rotation of the clutch mechanism effected upon the decay of the control impulse. For continuous operation of the clutch to be effected when the impulse is initiated and impressed on thecoil till, it. is seen that the armature 40% is attracted. The movement imparted thereto is sufllcient to permit the stop pawl All engaged by the stop 609 to pass the stops 409 and M0 on the arm 668 which in turn is supported on the extension arm 495.

The release of stop pawl Ml permits the plate M8 to be advanced to effect coupling of the pawl M2 and ratchet M3 which was just described. Upon deenergizatlon of the coil tilt the armature SM is restored to the normal position shown in Fig. 11 to block or restrain further movement of the plate M8 and thus efiect the declutching operation set forth.

The worm sleeve section 52 engages the worm gear 6! (Fig. 2) to drive the attached mechanism which will now be explained.

Coding commutator control means Referring now to Figs. 1, 2 and 3 of the drawings, the coding commutator control means, generally designated 53, will be described. This device, which will be hereinafter referred to as a program device, is explained in detail in Patent No. 1,791,927, dated February 10, 1931, therefore, the following brief description will suihce.

The program device comprises a plurality of control discs 59 mounted on a common shaft 60a. gear 80. The said gear is secured to the shaft 66a so as to rotate it upon actuation of the gear. The individual discs 59 are mounted on said shaft so that each and every disc may be removed at will and replaced by other discs as desired, and are adapted to be rotated by the fixed key 50c provided on said shaft. The individual discs are placed in a suitably spaced relation on the shaft as shown in Fig. 1 of the drawings, the washers On the same shaft with discs 59 is a large 

